Adaptive service chain management

ABSTRACT

Embodiments of the present invention provide methods, computer program products, and systems for fulfilling a service chain request. Embodiments of the present invention can be used to collect network data of a plurality of instances of services and connections between the plurality of instances of services and redefine service chains to direct flow to an alternative instance of a service responsive to determining that an instance of a service in a service chain has become inaccessible. Embodiments of the present invention can be used to fulfill a service chain request and avoid one or more instances of services (and/or connections there between) that could cause a delay between transmitting data packets through the service chain.

TECHNICAL FIELD

The present invention relates generally to the field of software-definednetworking, and more particularly to software-defined networkingcontrollers.

BACKGROUND

A data processing environment comprises a variety of hardware, software,and firmware networking components. A physical network, also called anunderlay, is a network defined using such components. An example of anetworking component in a physical network is a computing node. Acomputing node is a device that can offer a service (e.g., compression,encryption, firewall, decryption, etc.) and channel incoming data fromany of multiple input ports to the specific output port that will takethe data toward its intended destination. Multiple computing nodes canform a service chain.

Techniques are available presently to construct a logical network, alsoknown as a software defined network (SDN) overlay (hereinafterinterchangeably, “SDN” or “overlay”), from networking components of aphysical network. Essentially, networking components are abstracted intocorresponding logical or virtual representations, and the abstractionsare used to define the SDN. In other words, an SDN is a logical networkformed and operated using logical representations of underlyingnetworking components.

Physical networks usually exist within the demarcated boundary of thedata processing environment whose networking components are utilized inthe physical network. Unlike a physical network, an SDN can be designedto span across one or more data processing environments. For example,while a physical network may be contained within a datacenter, an SDNmay span across one or more datacenters.

As an example, a logical representation of a hypervisor can participatein an SDN, such that a function attributed to the logical representationof the hypervisor in the SDN is actually performed by the underlyinghypervisor component in the underlay. Similarly, a logicalrepresentation of a networking gateway can participate in an SDN, suchthat a function attributed to the logical representation of thenetworking gateway in the SDN is actually performed by the underlyingnetworking gateway component in the underlay.

In an SDN, because the actual networking components that perform thenetworking functions are abstracted into logical entities representingthe networking functionality offered by those components and not theactual implementations of those functionalities, something is needed todirect those networking functionalities into a functioning logicalnetwork. An SDN controller is a component that manages and operates thelogical networking components within an SDN. For example, an SDNcontroller manages flow entries of computing nodes forming a servicechain in an underlay network.

SUMMARY

In one embodiment of the present invention, a method for fulfilling aservice chain request is provided. The method includes collectingnetwork data of a plurality of instances of services and connectionsbetween the plurality of instances of services. The method furtherincludes, receiving a service chain request requiring a first servicechain. The method further includes responsive to determining that aninstance of a service in the first service chain is inaccessible,dynamically redefining the first service chain to direct flow to analternative instance of the service.

In another embodiment of the present invention, a computer programproduct for fulfilling a service chain request is provided. The computerprogram product includes one or more computer readable storage media andprogram instructions stored on the one or more computer readable storagemedia. The program instructions include program instructions to collectnetwork data of a plurality of instances of services and connectionsbetween the plurality of instances of services. The program instructionsfurther include program instructions to receive a service chain requestrequiring a first service chain. The program instructions furtherinclude responsive to determining that an instance of a service in thefirst service chain is inaccessible, dynamically redefining the firstservice chain to direct flow to an alternative instance of the service.

In yet another embodiment of the present invention, a computer systemfor fulfilling a service chain request is provided. The computer systemincludes one or more computer processors, one or more computer readablestorage media, and program instructions stored on the one or morecomputer readable storage media for execution by at least one of the oneor more processors. The program instructions include programinstructions to collect network data of a plurality of instances ofservices and connections between the plurality of instances of services.The program instructions further include program instructions to receivea service chain request requiring a first service chain. The programinstructions further include responsive to determining that an instanceof a service in the first service chain is inaccessible, dynamicallyredefining the first service chain to direct flow to an alternativeinstance of the service.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a functional block diagram illustrating a computingenvironment, in accordance with an embodiment of the present invention;

FIG. 2 is a flowchart illustrating operational steps for calculating adata path that fulfills a service chain request, in accordance with anembodiment of the present invention;

FIG. 3 is a flowchart illustrating operational steps for redefiningservice chains that contain an overloaded instance of a service, inaccordance with an embodiment of the present invention;

FIG. 4 is a block diagram of example data paths through which datapackets can be forwarded, in accordance with an embodiment of thepresent invention; and

FIG. 5 is a block diagram of internal and external components of thecomputer systems of FIG. 1, in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION

Embodiments of the present invention recognize that instances of aservice in a service chain can be overloaded (e.g., with many flowentries). For example, a computing node responsible for compression canbe overloaded with many flow entries and sending data packets to thatinstance of service may result in unwanted delay. A different computingnode offering an alternative instance of the same service (e.g.,compression), in a geographically different location, can sit idle withlittle to no installed flow entries. Thus, sending the data packet tothe different computing node providing the alternative instance of thesame service can alleviate delay that might occur due to overloadedcomputing nodes. Embodiments of the present invention provide efficientsolutions for making an SDN controller adaptive to changing conditionsof a service chain infrastructure spanning dispersed geographiclocations. In this manner, as discussed in greater detail in thisspecification, embodiments of the present invention can be used tocalculate an optimal service chain that excludes overloaded computingnodes in the service chain based, at least in part, on bandwidthavailability, latency, processing power, and traffic.

FIG. 1 is a functional block diagram of a computing environment 100, inaccordance with an embodiment of the present invention. Computingenvironment 100 includes a computer system 102, a computer system 122,and a computer system 124, interconnected via an underlay networks, 110,114, and 116. Computer system 102, computer system 122, and computersystem 124 can be desktop computers, laptop computers, server computers,or any other computer systems known in the art. In certain embodiments,computer system 102, computer system 122, and computer system 124represent computer systems utilizing clustered computers and componentsto act as a single pool of seamless resources when accessed throughnetworks 110, 114, and 116. For example, such embodiments may be used indata center, cloud computing, storage area network (SAN), and networkattached storage (NAS) applications. In certain embodiments, computersystem 102, computer system 122, and computer system 124 representvirtual machines. In general, computer system 102, computer system 122,and computer system 124 are representative of any electronic devices, orcombination of electronic devices, capable of executing machine-readableprogram instructions, as described in greater detail with regard to FIG.5.

Network 110, network 114, and network 118 include one or more respectiveservices 112 a-n, 116 a-n, and 120 a-n where services 112 a-n reside onnetwork 110, services 116 a-n reside on network 114, and services 120a-n reside on network 118. Network 110, network 114, and network 118 canbe, for example, a local area network (LAN), a wide area network (WAN)such as the Internet, or a combination of the two, and include wired,wireless, or fiber optic connections. Network 110, network 114, andnetwork 118 can be dispersed in geographically different locations. Forexample, network 110, network 114, and network 118 can each be indifferent areas of a region, in different regions, or any combination ofthe two. In general, network 110, network 114, and network 118 can beany combination of connections and protocols that will supportcommunications between computer system 102, services 112 a-n, 116 a-n,and 120 a-n, computer system 122, and computer system 124, in accordancewith a desired embodiment of the invention.

Services 112 a-n, services 116 a-n, and services 120 a-n are one or moredata processing services. For example, services 112 a-n, 116 a-n, and120 a-n, can be network devices that offer a plurality of instances ofparticular services (e.g., firewall, compression, encryption,decryption, decompression, intrusion detection, load balancer, networkaddress translation, etc.) to be performed on data packets that arereceived and transmitted through the network devices en route from asource computer system to an intended destination computer system. Theterm “service chain”, as used herein, refers to a specific sequence ofnetworks (e.g., network 110, network 114, and network 118) providingparticular services (e.g., firewall, compression, encryption,decryption, decompression, intrusion detection, load balancer, networkaddress translation, etc.) to be performed on data packets beingtransmitted towards their intended destinations. For example, a servicechain can include a sequence of networks comprising network 110,followed by network 114, and followed by network 118, where services 112a-n of network 110 perform compression services, services 116 a-n ofnetwork 114 perform encryption services, and services 120 a-n of network118 perform decryption services.

Services 112 a-n, services 116 a-n, and services 120 a-n representdifferent instances of particular services that can be in differentareas of a region, in different regions, or any combination of the two.In this embodiment, each respective group of services on a particularnetwork (e.g., services 112 a-n on network 110, services 116 a-n onnetwork 114, and services 120 a-n on network 118) can be configured toperform the same service. For example, service 112 a, service 112 b, andservice 112 c can be configured to encrypt data packets. In anotherexample, service 116 a, service 116 b, and service 116 c can beconfigured for compression, and so on for each respective group ofservices. In other embodiments, subgroups of services can be configuredon each particular network (e.g., a subgroup of services 112 a-n onnetwork 110 can be configured for encryption, while another subgroup ofservices 112 a-n on network 110 can be configured for compression). Forillustrative purposes, this embodiment may be discussed with respect toservices 112 a-n, services 116 a-n, and services 120 a-n as having thesame number of instances of services, it being understood that each ofservices 112 a-n, services 116 a-n, and services 120 a-n can have adifferent number of instances of services.

Each of services 112 a-n, services 116 a-n, and services 120 a-nincludes a respective flow entry manager (not shown) which interactswith an application 106 (e.g., through a software or hardware switch)and installs flow entries on respective services 112 a-n, services 116a-n, and services 120 a-n. The term “flow entry”, as used herein, refersto one or more rules and/or instructions that direct a service on howand where to transmit data packets. Each respective flow entry manageris capable of receiving data packets from, and sending data packets to,one or more services until the data packets reach their finaldestination (e.g., from computer system 122 to computer system 124).

Each respective flow entry manager can be configured to executenetworking functions of their respective network. In an embodiment, eachrespective flow entry manager can broadcast network data for theirrespective services. The term “network data”, as used herein, refers todetails of respective services and the connections between them. Forexample, each respective flow entry manager can broadcast network datacomprising, the network address of a service (e.g., the IP address), theMedia Access Control (MAC) address of the service, the computing powerof the service, the number of flow entries supported by the service(e.g., 100 entries), the amount of flow entries currently installed onthe service, and the bandwidth and latency of their respective networks.In other embodiments, SDN controller 104 can receive details forrespective instances of a service from a user.

Computer system 102 includes SDN controller 104 and data store 108. SDNcontroller 104 manages flow entries of services 112 a-n, services 116a-n, and services 120 a-n of respective networks 110, 114, and 118 basedon communications protocols. Communications protocols, for example, canallow SDN controller 104 to remotely add, modify, and remove packetmatching rules and actions, which allows SDN controller 104 to accessand control services 112 a-n, services 116 a-n, and services 120 a-n.SDN controller 104 may have a full view of services 112 a-n in network110, services 116 a-n in network 114, and services 120 a-n in network118. For illustrative purposes, this embodiment may be discussed withrespect to computer system 102 facilitating sending and receivingpackets of data along a service chain comprising one or more services112 a-n, 116 a-n, and 120 a-n, between computer system 122 and computersystem 124, it being understood that each of computer systems 102, 122,and 124 can facilitate sending and receiving packets of data from one ormore components in computing environment 100.

SDN Controller 104 includes application 106. Application 106 detectsservices 112 a-n, services 116 a-n, and services 120 a-n and maps all ofthe possible combinations of one or more instances of these servicesthrough which data packets can be sent (i.e., data paths) to satisfy arequested service chain, along with weighting data for the services andthe connections between them. In this embodiment, application 106generates a weighted graph, where services 112 a-n, 116 a-n, and 120 a-nare represented as nodes of the graph, and the connections between theservices are represented as edges of the graph. In other embodiments,application 106 can map the possible combinations of instances of theseservices in other forms, such as one or more tables or lists.

The weighting data is based on usage details of services 112 a-n, 116a-n, and 120 a-n and the connections between them. The term “usagedetails”, as used herein, refers to metrics used to measure service use(e.g., the computing power of the service, the number of flow entriessupported by the service and the amount of flow entries currentlyinstalled on the service, and/or the bandwidth and latency of theirrespective networks) and alerts SDN controller 104 that a service isoverloaded. In this embodiment, an instance of a service assigned ahigher weight indicates that a data packet would be processed faster onthat particular instance of the service (e.g., because that instance hasmore available computing resources and/or a greater capacity) than onanother instance of the service having a lower weight. Similarly, anedge (e.g., the connection between services 112 a and 116 a) assigned ahigher weight indicates that a data packet would be transmitted fasteron that particular connection (e.g., because that connection supportsfaster transmission rates and/or is less utilized) than an edge assigneda lower weight. In this embodiment, a numerical weighting scale is used,where lower numbers represent lesser weights and higher numbersrepresent greater weights. In other embodiments, any desirable weightingscale can be used. Furthermore, in this embodiment, the weighting ofparticular instances of services and particular connections can changedynamically according to changes in operating conditions and usage. Forexample, as a particular instance of a service becomes more utilized andapproaches a specified capacity, the weighting of that instance of theservice may be decreased.

In this embodiment, the usage details that are used to weight the nodes(i.e., services 112 a-n, 116 a-n, and services 120 a-n) include thecomputing power of the respective instances of services, the number offlow entries supported by the respective instances of services, and theamount of flow entries currently installed on the respective instancesof services. In other embodiments, other usage details can be used toweight the nodes. In this embodiment, the usage details that are used toweight the edges (i.e., the connection between instances of services)include bandwidth and network latency. In other embodiments, other usagedetails can be used to weight the edges.

In this embodiment, application 106 can further specify thresholds foreach metric used to measure usage details (e.g., computing power usage,flow entries that can be installed on a particular service, bandwidthusage, and latency). For example, application 106 can specify that athreshold of greater than or equal to 50% of the maximum computing powerusage, flow entries that can be installed, bandwidth availability, andlatency. Responsive to determining that the service has reached thespecified threshold, application 106 assigns the lowest weight to thatinstance of service, which can effectively exclude that service from anoptimal data path calculation that fulfills the service chain request.In other embodiments, the specified threshold can be configured to anyuser-defined threshold.

Application 106 also calculates an optimal data path that fulfills theservice chain request, based on the constructed weighted graph, as shownin greater detail in FIG. 4. Application 106 updates the generatedweighted graph representing the possible combinations of instances ofservice and connections between them that a data packet can take eachtime a data path is calculated that fulfills a service chain request toreflect the most current usage details of services 112 a-n, services 116a-n, and services 120 a-n.

SDN controller 104 can call application 106 to dynamically redefine aservice chain responsive to detecting an instance of a service beinginaccessible. In this embodiment, SDN controller 104 can detect aninstance of a service that is part of a service chain as inaccessiblewhen the instance of a service broadcasts an error notification to SDNcontroller 104 indicating it is overloaded, or when a threshold ofgreater than or equal to 50% of the maximum computing power usage, flowentries that can be installed, bandwidth availability, and latency isreached. In this embodiment, SDN controller 104 redefines a servicechain by removing the inaccessible instance of a service from theservice chain and selecting an alternative instance of the same servicebased on the constructed weighted graph, as shown in greater detail inFIG. 3.

Data store 108 stores the graph created and maintained by application106. Data store 108 can be implemented using any storage media known inthe art.

FIG. 2 is a flowchart 200 illustrating operational steps for calculatinga data path that fulfills a service chain request, in accordance with anembodiment of the present invention.

In step 202, application 106 receives a request for a service chain. Inthis embodiment, application 106 receives a request for a service chainfrom SDN controller 104. For example, SDN controller 104 can specify theservice chain to be firewall, compression, encryption, decompression,and decryption, in that order. In other embodiments, application 106 canreceive a request for desired services from one or more components incomputing environment 100.

In step 204, application 106 detects services 112 a-n, services 116 a-n,and services 120 a-n. In this embodiment, application 106 receives abroadcast from respective services 112 a-n, services 116 a-n, andservices 120 a-n, which allows application 106 to detect their presence.The broadcast allows services 112 a-n, services 116 a-n, and services120 a-n to communicate information about themselves to application 106.In this embodiment, the broadcast comprises the following: the networkaddress of a service, the MAC address of the service, the computingpower of the service, the number of flow entries supported by theservice, and the amount of flow entries currently installed on theservice. For example, the broadcast can contain the followinginformation: network Id is 192.168.100.3, the MAC address of service 112a is 00: 02: E3: 07: 25: 44, computing power of service 112 a is onebillion floating-point operations per second (flops), the number of flowentries supported is 100, and the number of installed flow entries is10. In other embodiments, application 106 can query each of services 112a-n, services 116 a-n, and services 120 a-n for the informationcontained in the broadcast.

In step 206, application 106 maps the usage details of network 110,network 114, and network 118, and their respective instances of services(e.g., services 112 a-n, services 116 a-n, and services 120 a-n) andgenerates a graph, where instances of services are represented as nodesof the graph and connections between instances of services arerepresented as edges of the graph. Application 106 can alternativelyaccess a previously generated graph (e.g., previously generated for aprior request for a service chain). In this embodiment, application 106generates a graph comprising all possible combinations of a one or moreinstances of services from the broadcast that application 106 receivedfrom each of services 112 a-n, 116 a-n, and 120 a-n, along withweighting data based on the usage details, as previously discussed. Eachcombination represents a possible data path from source to destination,through instances of services that fulfill the requested service chain.

For example, application 106 can generate a graph comprising allpossible combinations of services 112 a and 112 b of a firewall service,services 116 a-c of a compression service, and services 120 a and 120 bof a decompression service and the connection points between each ofservices 112 a and 112 b, services 116 a-c, and services 120 a and 120 b(e.g., twelve possible data paths for firewall, compression, anddecompression services).

In this embodiment, each usage detail associated with a node (i.e., aninstance of a service) is assigned a point value that is used todetermine the weight assigned to that instance of a service. In thisembodiment, the usage details that are used to weight the nodes (i.e.,services 112 a-n, 116 a-n, and services 120 a-n) include the computingpower usage of the respective instances of services, and the maximumcapacity of flow entries currently installed on the respective instancesof services. The highest total point value is assigned the highestweight, which, as previously discussed, indicates that instance has moreavailable computing resources and/or greater capacity. In otherembodiments, other usage details can be used to weight the nodes.

For example, the usage details could indicate that service 112 a has amaximum capacity of ten flow entries, with a last known number ofinstalled flow entries of zero, and a CPU usage of 25% of its totalcomputing power. In this example, application 106 would assign service112 a a point value of 10 for its flow entry capacity and a 5 for itscomputing power usage. Application 106 then adds the point valuesassigned to service 112 a to yield a total point value of 15. The usagedetails could further indicate that service 112 b also has a maximumcapacity of ten flow entries, with a last known number of installed flowentries of 5, but a CPU usage of 50% of its total computing power. Inthis example, application 106 can assign service 112 b a point value of10 for its flow entry capacity and a point value of 2.5 for its CPUusage. Application 106 then adds the point values assigned to service112 b to yield a total point value of 12.5. Accordingly, in thisexample, service 112 a is weighted more highly than service 112 b.

Similarly, each usage detail associated with an edge (i.e. connectionsbetween the instances of services) is assigned a point value that isused to determine the weight assigned to that edge. In this embodiment,the usage details that are used to include bandwidth and networklatency. The highest total point value is assigned the highest weight,which, as previously discussed indicates that connection supports fastertransmission rates and/or is less utilized. In other embodiments, otherusage details can be used to weight the edges.

In this embodiment, application 106 can be configured to assign a pointvalue to nodes and/or edges that effectively excludes those nodes and/oredges from a data path calculation to fulfill a service chain request.For example, application 106 can assign the lowest possible point valueto a node that satisfies the 50% threshold of its maximum computingpower usage and maximum amount of flow entries that can be installed, oran edge that satisfies the 50% threshold of its bandwidth availabilityand network latency.

In step 208, application 106 calculates an optimal data path for packetsthat fulfills the service chain request. In this embodiment, application106 calculates an optimal data path for packets that fulfills theservice chain request by identifying a data path having the greatestcumulative weight. The term, “greatest cumulative weight”, as usedherein, refers to the sum total of the weight of nodes (i.e., instancesof services) and edges (i.e., connections between the instances ofservice). For example, an optimal data path selected could be data pathA (e.g., from 112 a to 116 b, and from 116 b to 120 a) because thecumulative weight of 112 a, 116 b, 120 a, the connection between 112 aand 116 b, and the connection between 116 b to 120 a exceeds thecumulative weights of other data paths that could be used to fulfill theservice chain request.

In another example, a requested service chain can be firewall,compression, and intrusion detection, in that order. Application 106accesses the graph and identifies there are two data paths that includethe sequence of instances of services that fulfills the service chainrequest: data path A (e.g., from service 112 a to service 116 a, andfrom service 116 a to service 120 a) or data path B (e.g., from service112 a to service 116 b, and from service 116 b to service 120 a).Application 106 identifies that service 112 a has an assigned weight of10, that the connection between service 112 a to service 116 a has anassigned weight of 10, that service 116 a has an assigned weight of 2,that the connection between service 116 a and service 120 a has anassigned weight of 5, and that service 120 a has an assigned weight of10. Application 106 then adds the weights associated with thecorresponding nodes and connections for data path A to yield acumulative weight of 37.

Using the graph to calculate the cumulative weight of data path B,application 106 identifies that service 112 a has an assigned weight of10, that the connection between service 112 a to service 116 b has anassigned weight of 9, that service 116 b has an assigned weight of 5,that the connection between service 116 b and service 120 a has anassigned weight of 10, and that service 120 a has an assigned weight of10. Application 106 then adds the weights associated with thecorresponding nodes and connections for data path B to yield acumulative weight of 44. Accordingly, application 106 would select datapath B as the optimal data path that fulfills the service chain request.

In this embodiment, where an instance of a service satisfies itsconfigured threshold (i.e., becomes overloaded), application 106 canexclude that instance of the service from future calculated data paths,invalidate that instance of the service from all previously executeddata paths, and generate an optimal data path for fulfilling therequested service chain using the remaining instances of that service.For example, a requested service chain can be firewall, compression, andintrusion, in that order. The previously installed flow for that servicechain may have sent the data packets to service 112 a (firewall) locatedin region 1, service 116 b (compression) also located in region 1, andservice 120 c (intrusion detection) located in region 3. Responsive toreceiving an error notification from service 116 b indicating thatservice 116 b has satisfied its specified threshold, application 106 canaccess the graph of usage details and assign the lowest weight toservice 116 b, effectively excluding service 116 b from future optimaldata path calculations to fulfill service chain requests.

Application 106 can then identify, from the weighted graph, service 116c as an alternative instance of the same service for compression, andselect service 112 a, service 116 c, and service 120 c as the optimaldata path. Similarly, application 106 can also remove service 116 b fromany existing data paths. In this embodiment, for example, application106 can transmit instructions to flow managers on instances of all otherservices to remove a service that satisfies a specified threshold (e.g.,an overloaded instance of service, such as service 116 b) from theirflow tables, and replace the removed instance of service with analternative instance of the same service.

In step 210, application 106 executes the calculated data path. In thisembodiment, application 106 executes the calculated data path bytransmitting the calculated data path to SDN controller 104. SDNcontroller 104 installs the appropriate flow entries on the services inthe calculated data path, such that data packets can then be transmittedalong the calculated data path to fulfill the requested service chain.

In step 212, application 106 updates the graph and usage details. Inthis embodiment, application 106 updates usage details for the instancesof services in the calculated data path used to fulfill the servicechain request. For example, if the calculated data path used to fulfillthe service chain request includes services 112 a, 116 b, and 120 c,application 106 updates the usage details by increasing the count offlow entries installed on those services by one. In this embodiment,application 106 also updates usage details of connections betweeninstances of services to reflect any changes to bandwidth and networklatency.

Accordingly, in this embodiment, application 106 calculates an optimaldata path that fulfills a service chain request and also avoids one ormore instances of services (and/or connections therebetween) that couldcause a delay between transmitting data packets through the servicechain. In this manner, embodiments of the present invention can helpimprove data transfer speeds and make an SDN controller adaptive tochanging conditions of a service chain infrastructure spanning dispersedgeographic locations.

FIG. 3 is a flowchart 300 illustrating operational steps for redefiningservice chains that contain an overloaded instance of a service, inaccordance with an embodiment of the present invention. For example, theoperational steps of flowchart 300 can be performed at step 208 offlowchart 200.

In step 302, SDN controller 104 detects an overloaded instance of aservice in an executed service chain. In this embodiment, SDN controller104 can detect an overloaded instance of a service (i.e., aninaccessible instance of a service) responsive to receiving an errornotification from an instance of service indicating that it has becomeoverloaded or otherwise non-functional or inaccessible. In thisembodiment, SDN controller 104 can also detect an overloaded instance ofa service responsive to determining that one or more usage details ofthe service have reached a specified threshold (i.e., becomesoverloaded).

In step 304, SDN controller 104 invalidates the overloaded instance of aservice from service chains. In this embodiment, SDN controller 104invalidates the overloaded instance of a service from the executedservice chain and other existing service chains by transmittinginstructions to flow managers on instances of all other services toremove the overloaded instance of the service from their flow tables,which effectively removes the overloaded instance from the executedservice chain and other existing service chains by preventing datapackets from being transmitted to the overloaded instance of theservice.

In step 306, SDN controller 104 transmits instructions to application106 to exclude the overloaded instance from future service chaincalculations. In this embodiment, application 106 can access the graphof usage details and assign the lowest weight to the overloaded instanceof the service, which effectively excludes the overloaded instance ofthe service from future service chain calculations to fulfill servicechain requests.

In step 308, SDN controller 104 identifies an alternative instance ofthe same service having the greatest weight. In this embodiment, SDNcontroller 104 identifies an alternative instance of the same servicehaving the greatest weight by accessing the weighted graph. For example,an executed service chain for compression, encryption, and decryptioncould have an optimal data path from services 112 a to 116 a, and fromservices 116 a to service 120 a. In this example, SDN controller 104receives an error notification from 116 a indicating that 116 a hasbecome overloaded. Responsive to receiving the error notification, SDNcontroller 104 invalidates that overloaded instance (e.g., service 116a), transmits instructions to application 106 to exclude service 116 afrom future data path calculations, and identifies the alternativeinstances of the same service as services 116 b-d. SDN controller 104can further identify that service 116 c has the greatest assigned weight(e.g., because that instance has more available computing resourcesand/or a greater capacity) by accessing the weighted graph generated instep 206 of flowchart 200.

In step 310, SDN controller 104 executes the redefined service chainusing the identified alternative instance of the same service. In thisembodiment, SDN controller 104 executes the redefined service chain byinstalling flow entries on respective flow managers of the instances ofservices in the redefined service chain.

In step 312, SDN controller 104 redefines other existing service chainsthat contained the overloaded instance of a service. In this embodiment,SDN controller 104 redefines other existing service chains that includedthe overloaded instance of a service responsive to receiving a query foran alternative instance of the service from flow entry managers. Forexample, flow entry managers of respective instances of services thatremoved the overloaded instance of a service (responsive to receivinginstructions from SDN controller 104 to remove the overloaded instance)from their flow tables would not know where to forward data packets.These flow entry managers could then query SDN controller 104 for analternative instance of the overloaded instance of service. In thisembodiment, responsive to receiving a query from flow entry managers,SDN controller 104 redefines the service chain by identifyingalternative instances of the same service having the greatest weight,and executes the redefined service chain by transmitting instructions tothe flow entry managers of the instances of services to install thealternative instance of the same service in their respective flowtables, as previously discussed in steps 308 and 310.

FIG. 4 is a block diagram of example data paths through which datapackets can be forwarded, in accordance with an embodiment of thepresent invention. In this example, application 106 receives a servicechain request for data packets to be transmitted from computer system122 to computer system 124 that includes firewall, compression, andintrusion detection services, in that order. In this example, services112 a-d are instances of the firewall service, services 116 a-d areinstances of the compression service, and services 120 a-d are instancesof the intrusion detection service, where network 114, and network 118,are each located in a different geographic location. The dotted linesrepresent possible data paths between services 112 a-d, 116 a-d, and 120a-d that fulfill the service chain request. The solid line representsthe calculated optimal data path that fulfills the service chainrequest.

In this embodiment, application 106 calculates the optimal data path forpackets as being from service 112 a to service 116 b, and from service116 b to service 120 a, because this data path possesses the greatestcumulative weight. That is, the cumulative weight of 112 a, 116 b, 120a, edge 404, and edge 410 exceeds the cumulative weights of other datapaths that could have been used to fulfill the service chain request.

In this example, application 106 received an error notification fromservice 116 a, and determined that service 116 a is overloaded (denotedby an asterisk). Application 106 then invalidates service 116 a fromdata path calculations for fulfilling the service chain request.

Application 106 calculates an optimal data path to fulfill the servicechain request by accessing the weighted graph, identifying weights foralternative instances of the compression services, and identifying thedata path with this greatest cumulative weight containing thealternative instances for the compression services.

In this example, application 106 selects service 112 a because asbetween service 112 a-d, service 112 a has the highest assigned weightof 10. Application 106 then identifies services 116 b-d as availableinstances of the same compression service. Application 106 thenidentifies that services 116 b-d have the same weight assigned (e.g., 9)to each of them. As between services 116 b-d, application 106 wouldselect service 116 b because edge 404 between service 112 a and 116 bhad the highest weight (e.g., 10, indicating that a data packet would beprocessed faster on that particular connection (e.g., because thatconnection supports faster transmission rates and/or is less utilized).Edges 406 and 408 had assigned weights of 5 and 6, respectively. Edge402 had an assigned weight of 10 but would no longer be selected becausethis connection would send the data packet to service 116 a which hasbeen determined as an overloaded instance of a compression service.

Application 106 then identifies the assigned weights for the connectionsto services 120 a-d as well as the weights for each of services 120 a-d.For example, edges 410-416 could have the following weights: 8, 3, 5,and 4. Application 106 selects edge 410 because edge 410 has the highestweight.

Continuing the example, application 106 then identifies the weights forservices 120 a-b as 8, 9, 6, and 5. As between service 120 a and service120 b, application 106 would select service 120 a as the instance ofintrusion detection service even though service 120 b had the higherweight because edge 410 had a higher weight.

To complete the optimal data path calculation, application 106 sums theweights assigned to the nodes and connections that could fulfill theservice chain request. The cumulative weight of 112 a, 116 b, 120 b,edge 404, and edge 412 is 41 (e.g., 10+9+9+10 3). The cumulative weightof 112 a, 116 b, 120 c, edge 404, and edge 414 is 40 (e.g., 10+9+6+10+5). The cumulative weight of 112 a, 116 b, 120 d, edge 404, and edge416 is 38 (e.g., 10+9+6+10+4). The cumulative weight of 112 a, 116 b,120 a, edge 404, and edge 410 is 45 (e.g., 10 +9+8+10+8) and exceeds thecumulative weights of other data paths that could have fulfilled theservice chain request. It is therefore selected as the optimal data paththat fulfills the service chain request.

FIG. 5 is a block diagram of internal and external components of acomputer system 500, which is representative the computer systems andswitches of FIG. 1, in accordance with an embodiment of the presentinvention. It should be appreciated that FIG. 5 provides only anillustration of one implementation and does not imply any limitationswith regard to the environments in which different embodiments may beimplemented. In general, the components illustrated in FIG. 5 arerepresentative of any electronic device capable of executingmachine-readable program instructions. Examples of computer systems,environments, and/or configurations that may be represented by thecomponents illustrated in FIG. 5 include, but are not limited to,personal computer systems, server computer systems, thin clients, thickclients, laptop computer systems, tablet computer systems, cellulartelephones (e.g., smart phones), multiprocessor systems,microprocessor-based systems, network PCs, minicomputer systems,mainframe computer systems, and distributed cloud computing environmentsthat include any of the above systems or devices.

Computer system 500 includes communications fabric 502, which providesfor communications between one or more processors 504, memory 506,persistent storage 508, communications unit 512, and one or moreinput/output (I/O) interfaces 514. Communications fabric 502 can beimplemented with any architecture designed for passing data and/orcontrol information between processors (such as microprocessors,communications and network processors, etc.), system memory, peripheraldevices, and any other hardware components within a system. For example,communications fabric 502 can be implemented with one or more buses.

Memory 506 and persistent storage 508 are computer-readable storagemedia. In this embodiment, memory 506 includes random access memory(RAM) 516 and cache memory 518. In general, memory 506 can include anysuitable volatile or non-volatile computer-readable storage media.Software is stored in persistent storage 508 for execution and/or accessby one or more of the respective processors 504 via one or more memoriesof memory 506. Such software can be SDN controller 104, and application106, and/or any or all of flow entry managers.

Persistent storage 508 may include, for example, a plurality of magnetichard disk drives. Alternatively, or in addition to magnetic hard diskdrives, persistent storage 508 can include one or more solid state harddrives, semiconductor storage devices, read-only memories (ROM),erasable programmable read-only memories (EPROM), flash memories, or anyother computer-readable storage media that is capable of storing programinstructions or digital information.

The media used by persistent storage 508 can also be removable. Forexample, a removable hard drive can be used for persistent storage 508.Other examples include optical and magnetic disks, thumb drives, andsmart cards that are inserted into a drive for transfer onto anothercomputer-readable storage medium that is also part of persistent storage508.

Communications unit 512 provides for communications with other computersystems or devices via a network (e.g., network 110, network 114, and/ornetwork 118). In this exemplary embodiment, communications unit 512includes network adapters or interfaces such as a TCP/IP adapter cards,wireless Wi-Fi interface cards, or 3G or 4G wireless interface cards orother wired or wireless communication links. The network can comprise,for example, copper wires, optical fibers, wireless transmission,routers, firewalls, switches, gateway computers and/or edge servers.Software and data used to practice embodiments of the present inventioncan be downloaded to computer system 102 through communications unit 512(e.g., via the Internet, a local area network or other wide areanetwork). From communications unit 512, the software and data can beloaded onto persistent storage 508.

One or more I/O interfaces 514 allow for input and output of data withother devices that may be connected to computer system 500. For example,I/O interface 514 can provide a connection to one or more externaldevices 520 such as a keyboard, computer mouse, touch screen, virtualkeyboard, touch pad, pointing device, or other human interface devices.External devices 520 can also include portable computer-readable storagemedia such as, for example, thumb drives, portable optical or magneticdisks, and memory cards. I/O interface 514 also connects to display 522.

Display 522 provides a mechanism to display data to a user and can be,for example, a computer monitor. Display 522 can also be an incorporateddisplay and may function as a touch screen, such as a built-in displayof a tablet computer.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method for fulfilling a service chain request,the method comprising: receiving, by one or more computer processors, aservice chain request requiring a first service chain; and responsive todetermining that an instance of a service in the first service chain isinaccessible, dynamically redefining, by one or more computerprocessors, the first service chain to direct flow to an alternativeinstance of the service.
 2. The method of claim 1, wherein responsive todetermining that an instance of a service in the first service chain isinaccessible, dynamically redefining, by one or more computerprocessors, the first service chain to direct flow to an alternativeinstance of the service comprises: invalidating, by one or more computerprocessors, the inaccessible instance of the service in the firstservice chain; excluding, by one or more computer processors, theinaccessible instance of the service in the first service chain fromfuture service chain calculations; and identifying, by one or morecomputer processors, an alternative instance of the service in theplurality of instances of services.
 3. The method of claim 2, whereininvalidating, by one or more computer processors, the inaccessibleinstance of the service in the first service chain comprises:transmitting, by one or more computer processors, an instruction to oneor more of the plurality of instances of services to remove theinaccessible instance of the service from flow tables of the one or moreof the plurality of instances of services.
 4. The method of claim 2,wherein identifying, by one or more computer processors, an alternativeinstance of the service in the plurality of instances of servicescomprises: generating, by one or more computer processors, a weightedgraph, wherein instances of services that are assigned a greater pointvalue are weighted more heavily in the weighted graph than instances ofservices that are assigned a lesser point value, and connections thatare assigned a greater point value are weighted more heavily in theweighted graph than connections that are assigned a lesser point value;and selecting, by one or more computer processors, an alternativeinstance of the service having a greatest weight in the weighted graph.5. The method of claim 3, further comprising: receiving, by one or morecomputer processors, a query from a first instance of service having afirst flow table from which the inaccessible instance of the service wasremoved; and responsive to receiving the query, transmitting, by one ormore computer processors, an instruction to the first instance ofservice to install the alternative instance of the service in the firstflow table.
 6. The method of claim 1, wherein determining that aninstance of a service in the first service chain is inaccessiblecomprises: receiving, by one or more computer processors, an errormessage from a first instance of service of the plurality of instancesof services; and responsive to receiving the error message, determining,by one or more computer processors, that the first instance of serviceis inaccessible.
 7. The method of claim 1, wherein determining that aninstance of a service in the first service chain is inaccessiblecomprises: specifying, by one or more computer processors, a thresholdfor network data of a first instance of service of the plurality ofinstances of services; and responsive to determining that usage detailsof the first instance of service satisfy the specified threshold,determining, by one or more computer processors, that the first instanceof service is inaccessible.
 8. A computer program product for fulfillinga service chain request, the computer program product comprising: one ormore computer readable storage media and program instructions stored onthe one or more computer readable storage media, the programinstructions comprising: program instructions to receive a service chainrequest requiring a first service chain; and program instructions to,responsive to determining that an instance of a service in the firstservice chain is inaccessible, dynamically redefine the first servicechain to direct flow to an alternative instance of the service.
 9. Thecomputer program product of claim 8, wherein the program instructionsto, responsive to determining that an instance of a service in the firstservice chain is inaccessible, dynamically redefine the first servicechain to direct flow to an alternative instance of the service comprise:program instructions to invalidate the inaccessible instance of theservice in the first service chain; program instructions to exclude theinaccessible instance of the service in the first service chain fromfuture service chain calculations; and program instructions to identifyan alternative instance of the service in the plurality of instances ofservices.
 10. The computer program product of claim 9, wherein theprogram instructions to invalidate the inaccessible instance of theservice in the first service chain comprise: program instructions totransmit an instruction to one or more of the plurality of instances ofservices to remove the inaccessible instance of the service from flowtables of the one or more of the plurality of instances of services. 11.The computer program product of claim 9, wherein the programinstructions to identify an alternative instance of the service in theplurality of instances of services comprise: program instructions togenerate a weighted graph, wherein instances of services that areassigned a greater point value are weighted more heavily in the weightedgraph than instances of services that are assigned a lesser point value,and connections that are assigned a greater point value are weightedmore heavily in the weighted graph than connections that are assigned alesser point value; and program instructions to select an alternativeinstance of the service having a greatest weight in the weighted graph.12. The computer program product of claim 10, wherein the programinstructions stored on the one or more computer readable storage mediafurther comprise: program instructions to receive a query from a firstinstance of service having a first flow table from which theinaccessible instance of the service was removed; and programinstructions to, responsive to receiving the query, transmit aninstruction to the first instance of service to install the alternativeinstance of the service in the first flow table.
 13. The computerprogram product of claim 8, wherein the program instructions todetermine that an instance of a service in the first service chain isinaccessible comprise: program instructions to receive an error messagefrom a first instance of service of the plurality of instances ofservices; and program instructions to, responsive to receiving the errormessage, determine that the first instance of service is inaccessible.14. The computer program product of claim 8, wherein the programinstructions to determine that an instance of a service in the firstservice chain is inaccessible comprise: program instructions to specifya threshold for network data of a first instance of service of theplurality of instances of services; and program instructions to,responsive to determining that usage details of the first instance ofservice satisfy the specified threshold, determine that the firstinstance of service is inaccessible.
 15. A computer system forfulfilling a service chain request, the computer system comprising: oneor more computer processors; one or more computer readable storagemedia; and program instructions stored on the one or more computerreadable storage media for execution by at least one of the one or morecomputer processors, the program instructions comprising: programinstructions to receive a service chain request requiring a firstservice chain; and program instructions to, responsive to determiningthat an instance of a service in the first service chain isinaccessible, dynamically redefine the first service chain to directflow to an alternative instance of the service.
 16. The computer systemof claim 15, wherein the program instructions to, responsive todetermining that an instance of a service in the first service chain isinaccessible, dynamically redefine the first service chain to directflow to an alternative instance of the service comprise: programinstructions to invalidate the inaccessible instance of the service inthe first service chain; program instructions to exclude theinaccessible instance of the service in the first service chain fromfuture service chain calculations; and program instructions to identifyan alternative instance of the service in the plurality of instances ofservices.
 17. The computer system of claim 16, wherein the programinstructions to invalidate the inaccessible instance of the service inthe first service chain comprise: program instructions to transmit aninstruction to one or more of the plurality of instances of services toremove the inaccessible instance of the service from flow tables of theone or more of the plurality of instances of services.
 18. The computersystem of claim 16, wherein the program instructions to identify analternative instance of the service in the plurality of instances ofservices comprise: program instructions to generate a weighted graph,wherein instances of services that are assigned a greater point valueare weighted more heavily in the weighted graph than instances ofservices that are assigned a lesser point value, and connections thatare assigned a greater point value are weighted more heavily in theweighted graph than connections that are assigned a lesser point value;and program instructions to select an alternative instance of theservice having a greatest weight in the weighted graph.
 19. The computersystem of claim 17, wherein the program instructions stored on the oneor more computer readable storage media further comprise: programinstructions to receive a query from a first instance of service havinga first flow table from which the inaccessible instance of the servicewas removed; and program instructions to, responsive to receiving thequery, transmit an instruction to the first instance of service toinstall the alternative instance of the service in the first flow table.20. The computer system of claim 15, wherein the program instructions todetermine that an instance of a service in the first service chain isinaccessible comprise: program instructions to receive an error messagefrom a first instance of service of the plurality of instances ofservices; and program instructions to, responsive to receiving the errormessage, determine that the first instance of service is inaccessible.